Conveyor belt systems with symmetrical interlocking surfaces are known in the prior art. Such systems may employ projections, or cogs, on the interactive surface of the drive belt to improve flexibility of the belt thereby enabling the belt to pass around pulleys of relatively small diameter. Additionally, the projections may interact with apertures of mating geometry formed in the pulley, or with projection receiving grooves formed in the pulley in an attempt to improve alignment, or tracking and pulling, of the belt.
One such prior art conveyor belt system is described in my U.S. Pat. No. 4,011,939 which discloses a pulley with symmetrical cleat-receiving annular grooves for engaging cleats formed in longitudinal rows on the belt.
Another prior art conveyor belt system utilizing V-shaped projections that engage symmetrical V-shaped grooves in the pulley is described in U.S. Pat. No. 3,987,683 which utilizes side walls to further maintain lateral alignment.
Other prior art conveyor belt systems utilize symmetrical teeth like projections on the pulley and the tracking surface of the belts, such as the system described in French Pat. No. 1,069,964. Another system described in U.S. Pat. No. 3,722,962 uses projections on the belt coupled with placement of a rotatable drive mechanism on the sprocket of the pulley. One other prior art conveyor belt system described in U.S. Pat. No. 4,290,761 teaches cylindrical projections on the tracking surface of the belt for the purpose of belt repair and provision of traction.
Some of the above described symmetrical conveyor belt systems improve belt tracking, but none provide precise tracking and centering of the belt, and none are suitable for reversible conveyor belts systems because all require at least some re-alignment, or centering, prior to reversal of the conveyor belt.
Centering a conveyor belt prior to operation generally requires use of a conventional centering kit, or centering may be manually performed. The conveyor belt must be adjusted laterally and tensioned. All of the above prior art conveyor belt systems require that the system be "re-centered", or at the least, re-tensioned, prior to reversing the direction of travel of the belt.
My U.S. Pat. No. 4,449,958 described a drive pulley having recesses for engaging projections formed as truncated pyramids having a cylindrical portion extending therefrom for increasing positive tracking and drive. As described therein, the pulley was configured with either a combination of sockets and grooves, or just sockets, or just grooves. In another embodiment, a center portion of the pulley was configured with the truncated pyramid pattern for driving a mesh belt. The truncated pyramid arrangement disclosed in the '958 patent increased positive tracking with little creep of the belt at speeds up to one thousand (1000) feet per minute.
A heretofore unmet need exists for a conveyor belt system with precise tracking and centering, locking drive, improved positive drive force and timing without creep, the ability to operate in reverse without re-centering, the ability to operate at high speeds while utilizing substantially any diameter of pulley, the ability to operate at an increased pitch, and the ability to be configured to convey high impact loads without lateral displacement.